Step 2: Circuit Construction:

Take the power transistor 1351 and connect two wires to the middle terminal which is the collector terminal while connecting 1 wire each to the base and the emitter terminals as shown in the picture.

Now take 2 Iron nails. Connect 1 to the collector and the other to the base terminal.

You should now be left with 2 wires emitter and collector (since the collector terminal had two wires).Take the LED lights and the buzzer and connect them in parallel.Take their common positive and connect it to the emitter terminal of the power transistor while its negative terminal will be connected to the negative terminal of the battery.

The positive terminal of the battery will be connected to the collector terminal of the power transistor as in the picture.

Step 3: Testing:

After you have completed everything as stated in the second step, simply touch the nails with your hands and the buzzer should start operating.

Your body is acting as a conductor between the base and the collector terminals of the power transistor.

Since the base current required for the operation of a power transistor is very small therefore the buzzer starts operating without an issue.The LED lights however require a higher value of base current therefore they might not operate and even if they do, the illumination will be dim.

The above experiment proves that a human body is a conductor of electricity even though it is highly resistive.

Now take some water in a cup and dip the two nails in it.Make sure that they do not touch each other.

The water in between the two nails will act as a conductor and both the led's and the buzzer should start operating because the resistance of water is much lower than the resistance of a human body.

This experiment proves that water is a great conductor of electricity.